A. Least visible
Not crazy about seeing a sweep? This hidden device’s metal housing fits into a groove routed into a wood door’s bottom edge; the sweep automatically raises and lowers. When the door closes, a pin on one end is pushed in, lowering the gasket flush with the threshold. Opening the door releases the pin and lifts the sweep.
Shown: National Guard Auto Door Bottom 335N-36, $37; Zoro
B. Easiest to install
If you don’t have a solid-wood door (or don’t want to alter yours), a surface-mount automatic door bottom may work. Fastened to the door’s outside face, a spring-loaded vinyl strip swivels up when the door opens. It’s long lasting and won’t impede swing—but it will be visible from outside.
Shown: M-D Building Products Flex-O-Matic Door Sweep 07179, $11; Home Depot
C. Best for uneven floors
An automatic door bottom only maintains tight contact with a flat surface. If your threshold isn’t level, a brush-style sweep that conforms to the floor’s contours is a better option. The dense nylon bristles on this UL-listed, commercial-grade sweep block drafts and smoke.
Shown: Hager Door Bottom Sweep with Brush Insert, $16; Global Industrial